Vehicle drivetrain assembly and method for making the assembly

ABSTRACT

A vehicle drivetrain assembly (10) and method for making the assembly of first and second torque transmitting members (12, 14), one of which (12) is aluminum and the other of which (14) is steel, that are joined by an electromagnetic pulse weld (16) progressively applied along a radial direction relative to the axis (A) of assembly rotation so as to provide a lightweight construction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application Ser.No. 62/744,328 filed Oct. 11, 2018, the entire disclosure of which ishereby incorporated by reference.

TECHNICAL FIELD

This invention relates to a vehicle drivetrain assembly for use intransmitting torque between a vehicle engine and driving wheels, and theinvention also relates to a method for making the vehicle drivetrainassembly.

BACKGROUND ART

Drivetrain assemblies for vehicles are used to transmit torque between apower plant and driving wheels of a vehicle upon rotation about acentral axis during the vehicle driving.

SUMMARY OF THE INVENTION

The present invention provides a vehicle drivetrain assembly constructedof first and second torque transmitting members, one of which isaluminum and the other of which is steel, that are joined by anelectromagnetic pulse weld progressively applied along a radialdirection relative to the central axis of the assembly so as to providea lightweight construction.

A disclosed vehicle drivetrain assembly constructed according to theinvention includes a first torque transmitting member made of aluminumand has a planar plate portion with a round opening through which acentral axis of the assembly extends. The vehicle drivetrain assemblyalso includes a second torque transmitting member that is made of steeland has an annular connection location that faces axially relative tothe central axis and extends around the round opening of the planarplate portion of the first aluminum member. An electromagnetic pulseweld of the vehicle drivetrain assembly forms and connects the plateportion of the first aluminum member around its round opening with theconnection location of the second steel member.

As disclosed, the first aluminum member is a clutch hub or housinghaving an axially extending thin-walled spline portion, and the secondsteel member is a sun gear, a ring gear, a torque transmitting hub or ashaft.

As also disclosed by another embodiment of the vehicle drivetrainassembly, the electromagnetic pulse weld includes aluminum of a fourdigit grade whose first digit is lower than the first number of the fourdigit grade of aluminum of the first aluminum member remote from theweld.

A disclosed method for making a vehicle drivetrain assembly according tothe invention is performed by: positioning a planar plate portion of afirst aluminum torque transmitting member having a round opening with acentral axis in a spaced relationship adjacent an annular connectionlocation of a second steel torque transmitting member with theconnection location facing axially relative to the central axis andextending around the opening of the first aluminum member, and applyingan electromagnetic pulse weld that forms and welds the plate portion ofthe first aluminum member to the connection location of the second steelmember.

As disclosed, the method uses a first aluminum member that is a clutchhub or housing having an axially extending thin-walled spline portion,and uses a second steel member that is a sun gear, a ring gear, a torquetransmitting hub or a shaft.

As also disclosed by another practice of the method for making thevehicle drivetrain assembly, prior to performing the electromagneticpulse welding, a third member is positioned between the first aluminummember and the second steel member and is made of aluminum of a lowergrade than the first aluminum member. The third aluminum member has athickness less than 3 mm. and as disclosed a thickness of 1.5 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view without most of its background forillustrating a vehicle drivetrain assembly having connected aluminum andsteel members that are electromagnetically pulse welded to each other.

FIG. 1a is an enlarged view of a portion of FIG. 1 illustrating aportion of the vehicle drivetrain assembly where the aluminum member isformed and electromagnetically pulse welded to the steel member.

FIG. 1b is a partial sectional view taken along the direction of line 1b-1 b of FIG. 1 to illustrate a thin-walled spline portion of thealuminum member.

FIG. 2 is a sectional view of the vehicle drivetrain assembly taken asin FIG. 1 but before the electromagnetic pulse welding.

FIG. 2a is an enlarged view of a portion of FIG. 2 similar to FIG. 1abut before the forming and electromagnetic pulse welding.

FIG. 3 is a view of another embodiment of the vehicle drivetrainassembly taken in the same sectional manner as FIG. 1 but also havinganother aluminum member that is of a lower grade than the first aluminummember and that is located at the electromagnetic pulse weld forenhancing the weld strength.

FIG. 3a is an enlarged view of a portion of FIG. 3 similar to FIG. 1aand illustrating the additional aluminum member that is at the formedelectromagnetic pulse weld.

FIG. 4 is a view of the alternate embodiment of the vehicle drivetrainassembly shown in FIG. 3 and is similar to FIG. 2 before the forming andelectromagnetic pulse welding shown in FIGS. 3 and 3 a.

FIG. 4a is an enlarged view of a portion of FIG. 4 showing the vehicledrivetrain assembly components prior to the forming and electromagneticpulse welding.

FIG. 5 is a view that illustrates the manner in which the embodiment ofFIGS. 1 and 2 has its aluminum member electromagnetically pulse weldedin a progressive manner along a radial direction with respect to thecentral axis of the vehicle drivetrain assembly to form the weld.

FIG. 6 is a view similar to FIG. 5 that shows the manner in which thetwo aluminum members of the embodiment of FIGS. 3 and 4 areprogressively formed by the electromagnetic pulse welding along a radialdirection with respect to the central axis of the vehicle drivetrainassembly to form the weld.

FIG. 7 is a greatly enlarged view that illustrates the atomic bonding ofthe aluminum and steel members to each other.

FIG. 8 is a flow chart illustrating the manner in which the oneembodiment of the vehicle drivetrain assembly shown in FIGS. 1, 1 a, 2,2 a and 5 is processed.

FIG. 9 is another flow chart illustrating the manner in which the othervehicle drivetrain assembly shown in FIGS. 3, 3 a, 4, 4 a and 6 isprocessed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to FIG. 1, a vehicle drivetrain assembly generallyindicated by 10 is constructed in accordance with the invention by themethod of the invention and includes a first torque transmitting member12 made of aluminum, a second torque transmitting member 14 made ofsteel and an electromagnetic pulse weld 16 that connects the members toeach other as is hereinafter more fully described. Both the constructionof the vehicle drivetrain assembly 10 and the method of making theassembly will be described in an integrated manner to facilitate anunderstanding of different aspects of the invention.

With continuing reference to FIG. 1, the aluminum member 12 includes aplanar plate portion 18 of a round shape having a central round opening20 through which a rotational central axis A of the assembly extends.The second steel member 14 includes an annular connection location 22that faces axially relative to the central axis A as best shown in FIG.2b and that extends around the round opening 20 of the planar plateportion 18 of the aluminum member 12. The electromagnetic pulse weld 16as shown in FIG. 1b forms and connects the plate portion 18 of the firstaluminum member 12 around its round opening 20 with the connectionlocation 22 of the second steel member 14. Thus, the second steel member14 has durability for use as required while the first aluminum member 12advantageously provides the vehicle drivetrain assembly with a lighterconstruction than would be the case with making it of steel.

As illustrated in FIGS. 1 and 2, the first aluminum member 12 is aclutch hub or housing defining the plate portion 18 and also having anaxially extending thin-walled spline portion 24 which includesthin-walled splines 26 shown in FIG. 1 b.

As also shown in FIGS. 1 and 2, the second steel member 14 is shown as asun gear having helical teeth 28 and also can be constructed as a ringgear, torque transmitting hub or a shaft.

As illustrated in FIG. 5, the electromagnetic pulse welding forms theplate portion 18 of the aluminum member 12 progressively in a radialdirection with respect to the central axis of the assembly asillustrated by the schematic arrows 30 to form the weld 16 to the steelmember 14. The electromagnetic pulse welding provides the weld 16 asillustrated in the greatly magnified (1000×) view of FIG. 7 at an atomiclevel so as to secure the aluminum and steel to each other.

As illustrated in FIG. 8, the flow chart 32 illustrates in step 34 thepositioning of the aluminum and steel members adjacent to each other asalso shown in FIG. 2 and in step 36 shows applying the electromagneticpulse weld that forms the atomic bonding of the aluminum and steel.

With reference to FIGS. 3, 3 a, 4 and 4 a, another embodiment of thevehicle drivetrain assembly is indicated generally by 10′ and has thesame construction as the previously described embodiment except as willbe discussed. As such, like reference numerals are applied to the likecomponents thereof and much of the previous description is applicablesuch that no repetition thereof is necessary and thus will not berepeated. However, in embodiment 10′, another aluminum member 38 isinitially positioned as shown in FIG. 4a between the connection location22 of the steel member 14 and the plate portion 18 of the aluminummember 12 in preparation for the electromagnetic pulse welding. Thisaluminum member 38 is of a lower grade aluminum than the first aluminummember 12 and thus enhances the atomic bonding to the steel member 14.More specifically the aluminum member 38 is of a grade with a four digitmember whose first digit is lower than the first digit of the four digitmember of the grade of the first aluminum member 12 so as to form easierdue to its less strength resulting from less alloying. Further, thealuminum member 38 extends around the opening 20 of the plate portion 18of aluminum member 12 positioned adjacent the steel member connectionlocation 22 where the electromagnetic pulse welding provides the atomicbonding. Also, the aluminum member 38 has a thickness less than 3 mm.,preferably 1.5 mm. which herein means 1.5 mm. with a tolerance of plusor minus 10%, so the relatively thin aluminum has less mass than athicker aluminum member. Thus, the aluminum member 18 is acceleratedfaster and has a greater impact for providing the better atomic bondingwith the steel as is also provided by its less alloyed lower grade. Thethicker first aluminum member 12 also atomically bonds with the lowergrade aluminum of the thin aluminum member 38.

As illustrated in FIG. 6, the electromagnetic pulse welding forms boththe plate portion 18 of the aluminum member 12 and the aluminum member38 progressively in a radial direction with respect to the central axisof the assembly as illustrated by the schematic arrows 30 to form theweld 16 with the steel member 14.

As illustrated in FIG. 9, the flow chart 32′ illustrates in step 34′ thepositioning of the aluminum members 12 and 38 and the and steel member14 adjacent to each other as also shown in FIG. 3 and in the step 36shows the next step of applying the electromagnetic pulse weld thatforms the atomic bonding of the aluminum and steel.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the invention. Rather,the words used in the specification are words of description rather thanlimitation, and it is understood that various changes may be madewithout departing from the spirit and scope of the invention.Additionally, the features of various implementing embodiments may becombined to form further embodiments of the invention.

What is claimed is:
 1. A vehicle drivetrain assembly comprising: a firsttorque transmitting member make of aluminum and including a planar plateportion having a round opening through which a central axis of theassembly extends; a second torque transmitting member made of steel andincluding an annular connection location that faces axially relative tothe central axis and extends around the round opening of the planarplate portion of the first aluminum member; and an electromagnetic pulseweld that forms and connects the plate portion of the first aluminummember around its round opening with the connection location of thesecond steel member.
 2. A vehicle drivetrain assembly as in claim 1wherein the first aluminum member is a clutch hub or housing having anaxially extending thin-walled spline portion.
 3. A vehicle drivetrainassembly as in claim 1 wherein the second steel member is a sun gear, aring gear, a torque transmitting hub or a shaft.
 4. A vehicle drivetrainassembly as in claim 1 wherein the first aluminum member is a clutch hubor housing having an axially extending thin-walled spline portion andwherein the second steel member is a sun gear, a ring gear, a torquetransmitting hub or a shaft.
 5. A vehicle drivetrain assembly as inclaim 1 wherein the electromagnetic pulse weld includes aluminum of afour digit grade whose first number is lower than the first number ofthe four digit grade of aluminum of the first aluminum member remotefrom the weld.
 6. A method for making a vehicle drivetrain assemblycomprising: positioning a planar plate portion of a first aluminumtorque transmitting member having a round opening with a central axis ina spaced relationship adjacent an annular connection location of asecond steel torque transmitting member with the connection locationfacing axially relative to the central axis and extending around theopening of the first aluminum member; and applying an electromagneticpulse weld that forms and welds the plate portion of the first aluminummember to the connection location of the second steel member.
 7. Amethod for making a vehicle drivetrain assembly as in claim 6 whereinthe first aluminum member is a clutch hub or housing having an axiallyextending thin-walled spline portion.
 8. A method for making a vehicledrivetrain assembly claim 6 wherein the second steel member is a sungear, a ring gear, a torque transmitting hub or a shaft.
 9. A method formaking a vehicle drivetrain assembly as in claim 6 wherein the firstaluminum member is a clutch hub or housing having an axially extendingthin-walled spline portion and wherein the second steel member is a sungear, a ring gear, a torque transmitting hub or a shaft.
 10. A methodfor making a vehicle drivetrain assembly as in claim 6 wherein a thirdmember is positioned between the first aluminum member and the secondsteel member and is made of aluminum of a lower grade than the firstaluminum member.
 11. A method for making a vehicle drivetrain assemblyas in claim 6 wherein the third aluminum member has a thickness lessthan 3 mm.
 12. A method for making a vehicle drivetrain assembly as inclaim 6 wherein the third aluminum member has a thickness of 1.5 mm.